JPH0511532B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an injection molding machine, and particularly to an injection molding machine having a function of determining the quality of molded products.

[Conventional technology]

In order to obtain a highly accurate molded product, it is necessary to constantly monitor the quality of the molded product during the molding cycle. In this case, it is insufficient to simply monitor the filling pressure at the time of completion of injection, and it is necessary to continuously monitor the injection pressure from the start of injection of the molding material into the mold until the completion of filling.

Conventionally, this type of monitoring method involves measuring the resin pressure inside the mold and detecting its peak pressure, or as described in Japanese Patent Application Laid-Open No. 59-224323, There is a method of monitoring by measuring the waveform of the resin pressure inside and performing comparison calculations over time.

[Problem to be solved by the invention]

However, with conventional molding condition monitoring methods,
Since the monitoring is based only on the resin pressure and on the waveform variation with respect to time on the horizontal axis, it may be determined that the product is defective even though it is actually a good product. For example, after a minute delay from the start of injection,
This tends to occur when the screw starts to move,
There were many inconveniences in actual operation and problems with reliability.

The present invention has been made in view of the above-mentioned state of the prior art, and an object of the present invention is to provide an injection molding machine in which the relationship between the positional fluctuation of the injection screw and the injection pressure can be monitored. .

[Means to solve the problem]

In order to achieve the above object, the present invention provides: a heating cylinder having a nozzle body at its tip; an injection screw disposed rotatably and axially movably within the heating cylinder; and a mold for inserting the injection screw into a mold. push it in the direction
The present invention is directed to an injection molding machine equipped with an extrusion mechanism consisting of, for example, a hydraulic cylinder, which injects molten molding material into a mold from a nozzle body of the heating cylinder.

and detecting the position of the injection screw;
a position detecting means, such as a potentiometer; and an injection pressure detecting means, such as a pressure sensor attached to the hydraulic cylinder, for detecting the injection pressure, such as the injection hydraulic pressure, of the molding material as it is extruded by the extrusion mechanism. A first storage section comprising, for example, a sampling data storage section, which stores the position information of the injection screw from the position detection means and the injection pressure information from the injection pressure detection means; at the time, storing the data stored in the first storage unit as non-defective data;
a second storage section including, for example, a non-defective product data storage section; a calculation section that rearranges the data in each of these storage sections in accordance with the relationship between the injection screw position and the injection pressure of the molding material from the nozzle body; The apparatus is characterized by being provided with a comparison calculation section that compares the measured data and reference data rearranged by the calculation section for each injection screw position and determines the molding state of the shot before opening the mold. be.

[Effect]

The present invention has the above-mentioned configuration, and since the change in injection pressure for each position of the injection screw is captured as a fluctuating waveform and can be compared with a standard waveform, it is possible to accurately determine the quality of molded products. Therefore, reliability can be improved.

Embodiments of the present invention will be described in detail below with reference to the drawings.

1 to 3 are diagrams for explaining embodiments of the present invention, in which FIG. 1 is a block diagram of an injection molding machine, FIG. 2 is a waveform diagram showing the relationship of injection oil pressure to the forward position of the screw, and FIG. FIG. 3 is a flowchart showing a processing example of the present invention.

In FIG. 1, 1 is an injection molding machine, and 2 is a molding state monitoring device that monitors the molding state based on the position of the injection screw of the injection molding machine 1 and the injection oil pressure of the injection cylinder.

The pellet-like synthetic resin material 12 supplied from the hopper 11 is kneaded and plasticized by the rotation of the screw 13 and becomes a molten state, and the nozzle body 14
is injected into the mold 3 from the tip. Screw 1
3 is an actuator 16 in the hydraulic cylinder 15;
It moves forward (moves toward the mold) by oil supplied to the hydraulic cylinder 15. Mold 3 is
It consists of a fixed mold 4 disposed on the side of the nozzle body 14, and a movable mold 5 that is in close contact with the fixed mold 4 and is moved to take out the molded product after solidification.

A rack gear 42 is attached to the actuator 16 via a connecting bar 41, and a pinion 43 that meshes with the rack gear 42 is disposed. This pinion 4
3 is provided with a rotary potentiometer 44 that rotates synchronously. Furthermore, hydraulic cylinder 1
5 is provided with a pressure sensor 45 for detecting injection oil pressure.

The output signals of the potentiometer 44 and the pressure sensor 45 are output to an analog-to-digital (A/D) converter 22 in a time-division manner by a multiplexer 21. The position information and pressure information thus A/D converted are stored as data in the sampling data storage section 23. This sampling data storage unit 23 includes a standard time signal generation unit 2 that sets the time for sampling work.
6 is connected. The information on time vs. screw position and time vs. injection oil pressure stored in the sampling data storage section 23 is rearranged by the calculation section 27 as information on screw position vs. injection oil pressure.

The pulse signal generator 24 is configured so that the operator manually presses a button to send out a pulse when good molding starts to appear. The information rearranged by the arithmetic unit 27 as described above is transferred to the non-defective data storage unit 28 as non-defective data when the pulse signal generator 24 outputs a pulse signal.

The outputs of the calculation section 27 and the non-defective data storage section 28 are compared by the comparison calculation section 29 with each of the standard injection hydraulic pressures preset in the tolerance range setting device 30 for each screw position, and the deviation is checked. It is done. The comparison calculation section 29 has a display section 31.
and an alarm output section 32 are connected, and the comparison calculation results are displayed in the form of a waveform on a CRT display 33 as shown in FIG. Furthermore, when the calculation result exceeds the allowable value, the alarm device 34 is activated to issue an alarm.

Based on the above configuration, the operation in the injection cycle will be explained with reference to the flowchart of FIG. 3.

For each injection cycle, the device is activated based on the start of injection. The position of the injection screw 13 is determined by the potentiometer 44 at every fixed time period (for example, 5/100 seconds) generated from the standard time signal generator 26.
multiplexer (MUX) 2
1 is switched to select the injection oil pressure detected by the pressure sensor 45 and stored in the sampling data storage section 23. In this way, the two detection contents are alternately stored in the sampling data storage section 23 at regular intervals, and this process is executed sequentially from the start of injection and filling to the completion of charging (step 401).

The information stored in the sampling data storage unit 23 is used by the calculation unit 27 to calculate (injection speed = difference in position/difference in time) and convert it into data of screw position vs. injection oil pressure and screw position vs. injection speed. Convert (step 402).

When the injection molding machine is operating smoothly and a good product begins to be stably molded, the operator operates the switch of the pulse signal generator 24. Through this operation, the measurement calculation data stored in the calculation unit 27 is transferred to the non-defective data storage unit 28 and stored as non-defective data. The data stored in the non-defective data storage section 28 is used as reference data for subsequent injection hydraulic pressure waveforms and injection speed waveforms.

When the latest sampling data is stored in the sampling data storage section 23 at the time of the next shot, the comparison calculation section 29 compares and calculates the injection speed values and injection oil pressure values for all positions of the screw 13 with the reference data. Ru.

It is compared whether the calculation result is within the range set by the allowable range setter 30 (the range indicated by the dotted line in FIG. 2) (step 403). If the calculation result is within the allowable range, it is considered normal (i.e., a good product), and if it is outside the range (i.e., a defective product) (Yes in step 404), the alarm device 34 is activated via the alarm output section 32. , sound or display an alarm.

Note that the waveform as shown in FIG. 2 is displayed on the display section 31.
The waveform is displayed on the CRT display 33 via.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to monitor the molding state with high precision in response to the actual quality of the molded product. Furthermore, since the molding state can be displayed as a waveform of injection pressure with respect to the screw position on the horizontal axis, monitoring becomes easy. In particular, it eliminates the variation in dead time (the time from when the injection start signal is issued to when the injection operation actually starts) as in the conventional method, and it also makes it possible to discover problems with the waveform purely related to the injection position, and to investigate the cause and take countermeasures. can be implemented as soon as possible.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an injection molding machine according to an embodiment of the present invention, Fig. 2 is a waveform diagram showing the relationship between the injection oil pressure and the forward position of the screw, and Fig. 3 is a flowchart showing an example of the process of the present invention. be. 1... Injection molding machine, 2... Molding condition monitoring device,
3... Mold, 13... Screw, 16... Actuator, 23... Sampling data storage section, 24... Pulse signal generator, 27... Arithmetic section, 28... Good product data storage section, 29... Comparison Arithmetic unit, 30... Tolerance range setter, 31... Display unit, 32... Alarm output unit, 33... CRT display, 34... Alarm device, 44... Potentiometer, 45... Pressure sensor.

Claims (1)

[Claims] 1. A heating cylinder having a nozzle body at its tip, an injection screw disposed rotatably and movably in the axial direction within the heating cylinder, and an injection screw for extruding the injection screw toward the mold. ,
An injection molding machine equipped with an extrusion mechanism that injects the molten molding material into the mold from the nozzle body of the heating cylinder, comprising: a position detection means for detecting the position of the injection screw; and a position detection means for detecting the position of the injection screw; injection pressure detection means for detecting the injection pressure; a first storage section for storing position information of the injection screw from the position detection means; and injection pressure information from the injection pressure detection means; molding of non-defective products is possible. At the point in time, a second storage section stores the data stored in the first storage section as non-defective data, and the data in each of these storage sections is transferred to the injection screw position and the molding material from the nozzle body. A calculation section rearranges the data in relation to the injection pressure, and compares the measured data rearranged by the calculation section with reference data for each injection screw position to determine the molding condition of the shot before opening the mold. An injection molding machine characterized by being provided with a comparison calculation section.